Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were ra...Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.展开更多
We present analog clocks fitted to the Mars solar day.These clocks use the standard Earth-based second of the International System of Units(SI)as their operational unit of time,unlike current practice for Mars timekee...We present analog clocks fitted to the Mars solar day.These clocks use the standard Earth-based second of the International System of Units(SI)as their operational unit of time,unlike current practice for Mars timekeeping.We discuss the importance of preserving the SI second.On this basis,we identify the two analog clocks most suitable for public use by a future Mars population.These are a 20-hour clock with a hand motion similar to that of the standard Earth clock,and a 24-hour clock with a novel“Martian”hand motion which strikes the hour when all 3 hands converge onto that hour mark on the dial.Both clocks have Earth-day equivalents to assist learning.We also present a 24-hour“SpaceClock”,similar to the Martian clock but with no favored reference plane,hence equally readable from any viewing orientation.展开更多
The circadian clock is a highly hierarchical network of endogenous pacemakers that primarily maintains and directs oscillations through transcriptional and translational feedback loops,which modulates an approximately...The circadian clock is a highly hierarchical network of endogenous pacemakers that primarily maintains and directs oscillations through transcriptional and translational feedback loops,which modulates an approximately 24-h cycle of endocrine and metabolic rhythms within cells and tissues.While circadian clocks regulate metabolic processes and related physiology,emerging evidence indicates that metabolism and circadian rhythm are intimately intertwined.In this review,we highlight the concept of metabolites,including lipids and other polar metabolites generated from intestinal microbial metabolism and nutrient intake,as time cues that drive changes in circadian rhythms,which in turn influence metabolism and aging.Furthermore,we discuss the roles of functional metabolites as circadian cues,paving a new direction on potential intervention targets of circadian disruption,pathological aging,as well as metabolic diseases that are clinically important.展开更多
The plant circadian clock temporally drives gene expression throughout the day and coordinates various physiological processes with diurnal environmental changes. It is essential for conferring plant fitness and compe...The plant circadian clock temporally drives gene expression throughout the day and coordinates various physiological processes with diurnal environmental changes. It is essential for conferring plant fitness and competitive advantages to survive and thrive under natural conditions through the circadian control of gene transcription. Chinese cabbage(Brassica rapa ssp. pekinensis) is an economically important vegetable crop worldwide, although there is little information concerning its circadian clock system. Here we found that gene expression patterns are affected bycircadian oscillators at both the transcriptional and post-transcriptional levels in Chinese cabbage. Time-course RNA-seq analyses were conducted on two short-period lines(SPcc-1 and SPcc-2) and two long-period lines(LPcc-1 and LPcc-2) under constant light. The results showed that 32.7–50.5% of the genes were regulated bythe circadian oscillator and the expression peaks of cycling genes appeared earlier in short-period lines than long-period lines. In addition, approximately 250 splicing events exhibited circadian regulation, with intron retention(IR) accounting for a large proportion. Rhythmically spliced genes included the clock genes LATE ELONGATEDHYPOCOTYL(BrLHY), REVEILLE 2(BrRVE2) and EARLY FLOWERING 3(BrELF3). We also found that thecircadian oscillator could notably influence the diurnal expression patterns of genes that are associated with glucose metabolism via photosynthesis, the Calvin cycle and the tricarboxylic acid(TCA) cycle at both the transcriptional andpost-transcriptional levels. The collective results of this study demonstrate that circadian-regulated physiological processes contribute to Chinese cabbage growth and development.展开更多
The circadian clock is an important internal time regulatory system for a range of physiological and behavioral rhythms within living organisms.Testosterone,as one of the most critical sex hormones,is essential for th...The circadian clock is an important internal time regulatory system for a range of physiological and behavioral rhythms within living organisms.Testosterone,as one of the most critical sex hormones,is essential for the development of the reproductive system,maintenance of reproductive function,and the overall health of males.The secretion of testosterone in mammals is characterized by distinct circadian rhythms and is closely associated with the regulation of circadian clock genes.Here we review the central and peripheral regulatory mechanisms underlying the influence of circadian clock genes upon testosterone synthesis.We also examined the specific effects of these genes on the occurrence,development,and treatment of common male diseases,including late-onset hypogonadism,erectile dysfunction,male infertility,and prostate cancer.展开更多
Clock synchronization has important applications in multi-agent collaboration(such as drone light shows,intelligent transportation systems,and game AI),group decision-making,and emergency rescue operations.Synchroniza...Clock synchronization has important applications in multi-agent collaboration(such as drone light shows,intelligent transportation systems,and game AI),group decision-making,and emergency rescue operations.Synchronization method based on pulse-coupled oscillators(PCOs)provides an effective solution for clock synchronization in wireless networks.However,the existing clock synchronization algorithms in multi-agent ad hoc networks are difficult to meet the requirements of high precision and high stability of synchronization clock in group cooperation.Hence,this paper constructs a network model,named DAUNet(unsupervised neural network based on dual attention),to enhance clock synchronization accuracy in multi-agent wireless ad hoc networks.Specifically,we design an unsupervised distributed neural network framework as the backbone,building upon classical PCO-based synchronization methods.This framework resolves issues such as prolonged time synchronization message exchange between nodes,difficulties in centralized node coordination,and challenges in distributed training.Furthermore,we introduce a dual-attention mechanism as the core module of DAUNet.By integrating a Multi-Head Attention module and a Gated Attention module,the model significantly improves information extraction capabilities while reducing computational complexity,effectively mitigating synchronization inaccuracies and instability in multi-agent ad hoc networks.To evaluate the effectiveness of the proposed model,comparative experiments and ablation studies were conducted against classical methods and existing deep learning models.The research results show that,compared with the deep learning networks based on DASA and LSTM,DAUNet can reduce the mean normalized phase difference(NPD)by 1 to 2 orders of magnitude.Compared with the attention models based on additive attention and self-attention mechanisms,the performance of DAUNet has improved by more than ten times.This study demonstrates DAUNet’s potential in advancing multi-agent ad hoc networking technologies.展开更多
A progressive decline in fertility is a well-documented aspect of female aging and is associated with a range of cellular and molecular alterations,including genomic instability and modifications in epigenetic regulat...A progressive decline in fertility is a well-documented aspect of female aging and is associated with a range of cellular and molecular alterations,including genomic instability and modifications in epigenetic regulation.Epigenetic clocks,which estimate biological age based on DNA methylation patterns,have been extensively utilized to evaluate general health status and the risk of various diseases.Despite their broad application,the utility of epigenetic clocks in assessing female reproductive health remains only partially characterized.This minireview consolidates recent advancements in the application of epigenetic clocks to evaluate the functional status of the female reproductive system.The objective is to investigate their potential for quantifying and predicting the biological age of reproductive tissues,thereby establishing a theoretical basis for clinical applications in reproductive medicine.To date,no comprehensive minireview has systematically examined multi-tissue epigenetic clock models in the context of female reproductive aging,positioning this minireview as a novel contribution to the field.展开更多
Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonst...Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonstrate a 459 nm optical clock based on the 6S_(1/2)-7P_(1/2)transition in thermal^(133)Cs atoms.Two methods,modulation transfer spectroscopy(MTS)and frequency modulation spectroscopy(FMS),are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition.The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7×10^(-13)/√t and 6.4×10^(-13)/√t,respectively,at the averaging time t.The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing.The resultant 1470 nm output power reaches over 10μW and the pump-beam-induced light shift is estimated to be 2π×11 Hz with a fractional uncertainty of 2.4×10^(-18).These results demonstrate the feasibility of hybridizing passive and active optical clocks,providing a promising route toward compact multi-wavelength optical frequency standards.展开更多
A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias pr...A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias prediction.Wavelet analysis was first used to break down the satellite clock frequency data into several levels,producing high and low frequency coefficients for each layer.The correlation coefficients of the high and low frequency coefficients in each of the three sub-intervals created by splitting these coefficients were then determined.The major noise region—the sub-interval with the lowest correlation coefficient—was chosen for thresholding treatment and noise threshold computation.The clock frequency data was then processed using wavelet reconstruction and reconverted to clock data.Lastly,three different kinds of satellite clock data—RTS,whu-o,and IGS-F—were used to confirm the produced data.Our method enhanced the stability of the Quadratic Polynomial(QP)model’s predictions for the C16 satellite by about 40%,according to the results.The accuracy and stability of the Auto Regression Integrated Moving Average(ARIMA)model improved up to 41.8%and 14.2%,respectively,whilst the Wavelet Neural Network(WNN)model improved by roughly 27.8%and 63.6%,respectively.Although our method has little effect on forecasting IGS-F series satellites,the experimental findings show that it can improve the accuracy and stability of QP,ARIMA,and WNN model forecasts for RTS and whu-o satellite clock bias.展开更多
The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity...The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity.Owing to their ultra-high accuracy and stability,state-of-the-art optical lattice clocks have enabled resolving the gravitational redshift with a millimeter-scale height difference.Further reducing the vertical inter-clock separation down to the sub-millimeter level and especially shortening the required measurement time may be achieved by employing spin squeezing.Here,we theoretically investigate the spin-squeezing-enhanced differential frequency comparison between two optical clocks within a lattice-trapped cloud of^(171)Yb atoms.The numerical results illustrate that for a sample of 10^(4)atoms,the atomic-collision-limited resolution of the vertical separation between two clocks can reach 0.48 mm,corresponding to a fractional gravitational redshift at the 10^(-20)level.In addition,the required averaging time may be reduced to less than one hundredth of that of conventional clocks with independent atoms.Our work opens a door to the future spin-squeezing-enhanced test of general relativity.展开更多
This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electric...This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.展开更多
The circadian clock is a highly conserved timekeeping system in organisms,which maintains physiological homeostasis by precisely regulating periodic fluctuations in gene expression.Substantial clinical and experimenta...The circadian clock is a highly conserved timekeeping system in organisms,which maintains physiological homeostasis by precisely regulating periodic fluctuations in gene expression.Substantial clinical and experimental evidence has established a close association between circadian rhythm disruption and the development of various malignancies.Research has revealed characteristic alterations in the circadian gene expression profiles in tumor tissues,primarily manifested as a dysfunction of core clock components(particularly circadian locomotor output cycles kaput(CLOCK)and brain and muscle ARNT-like 1(BMAL1))and the widespread dysregulation of their downstream target genes.Notably,CLOCK demonstrates non-canonical oncogenic functions,including epigenetic regulation via histone acetyltransferase activity and the circadian-independent modulation of cancer pathways.This review systematically elaborates on the oncogenic mechanisms mediated by CLOCK/BMAL1,encompassing multidimensional effects such as cell cycle control,DNA damage response,metabolic reprogramming,and tumor microenvironment(TME)remodeling.Regarding the therapeutic strategies,we focus on cutting-edge approaches such as chrononutritional interventions,chronopharmacological modulation,and treatment regimen optimization,along with a discussion of future perspectives.The research breakthroughs highlighted in this work not only deepen our understanding of the crucial role of circadian regulation in cancer biology but also provide novel insights for the development of chronotherapeutic oncology,particularly through targeting the non-canonical functions of circadian proteins to develop innovative anti-cancer strategies.展开更多
When applying Grover＇s algorithm to an unordered database, the probabifity of obtaining correct results usually decreases as the quantity of target increases. A four-phase improvement of Grover＇s algorithm is propos...When applying Grover＇s algorithm to an unordered database, the probabifity of obtaining correct results usually decreases as the quantity of target increases. A four-phase improvement of Grover＇s algorithm is proposed to fix the deficiency, and the unitary and the phase-matching condition are also proposed. With this improved scheme, when the proportion of target is over 1/3, the probability of obtaining correct results is greater than 97.82% with only one iteration using two phases. When the computational complexity is O（ √M/N）, the algorithm can succeed with a probability no less than 99.63%.展开更多
文摘Objective To investigate the structural changes of rat thoracic aorta and changes in expression levels of Bmal1 and cyclins in thoracic aorta endothelial cells following heat stress.Methods Twenty male SD rats were randomized equally into control group and heat stress group.After exposure to 32℃for 2 weeks in the latter group,the rats were examined for histopathological changes and Bmal1 expression in the thoracic aorta using HE staining and immunohistochemistry.In the cell experiments,cultured rat thoracic aortic endothelial cells(RTAECs)were incubated at 40℃for 12 h with or without prior transfection with a Bmal1-specific small interfering RNA(si-Bmal1)or a negative sequence.In both rat thoracic aorta and RTAECs,the expressions of Bmal1,the cell cycle proteins CDK1,CDK4,CDK6,and cyclin B1,and apoptosis-related proteins Bax and Bcl-2 were detected using Western blotting.TUNEL staining was used to detect cell apoptosis in rat thoracic aorta,and the changes in cell cycle distribution and apoptosis in RTAECs were analyzed with flow cytometry.Results Compared with the control rats,the rats exposed to heat stress showed significantly increased blood pressures and lowered heart rate with elastic fiber disruption and increased expressions of Bmal1,cyclin B1 and CDK1 in the thoracic aorta(P<0.05).In cultured RTAECs,heat stress caused significant increase of Bmal1,cyclin B1 and CDK1 protein expression levels,which were obviously lowered in cells with prior si-Bmal1 transfection.Bmal1 knockdown also inhibited heat stress-induced increase of apoptosis in RTAECs as evidenced by decreased expression of Bax and increased expression of Bcl-2.Conclusion Heat stress upregulates Bmal1 expression and causes alterations in expressions of cyclins to trigger apoptosis of rat thoracic aorta endothelial cells,which can be partly alleviated by suppressing Bmal1 expression.
文摘We present analog clocks fitted to the Mars solar day.These clocks use the standard Earth-based second of the International System of Units(SI)as their operational unit of time,unlike current practice for Mars timekeeping.We discuss the importance of preserving the SI second.On this basis,we identify the two analog clocks most suitable for public use by a future Mars population.These are a 20-hour clock with a hand motion similar to that of the standard Earth clock,and a 24-hour clock with a novel“Martian”hand motion which strikes the hour when all 3 hands converge onto that hour mark on the dial.Both clocks have Earth-day equivalents to assist learning.We also present a 24-hour“SpaceClock”,similar to the Martian clock but with no favored reference plane,hence equally readable from any viewing orientation.
基金supported by grants from the Chinese Academy of Sciences(XDB39050800)the Major Project of Guangzhou National Laboratory(GZNL2024A03013)the National Natural Science Foundation of China(92357308 and 32321004)。
文摘The circadian clock is a highly hierarchical network of endogenous pacemakers that primarily maintains and directs oscillations through transcriptional and translational feedback loops,which modulates an approximately 24-h cycle of endocrine and metabolic rhythms within cells and tissues.While circadian clocks regulate metabolic processes and related physiology,emerging evidence indicates that metabolism and circadian rhythm are intimately intertwined.In this review,we highlight the concept of metabolites,including lipids and other polar metabolites generated from intestinal microbial metabolism and nutrient intake,as time cues that drive changes in circadian rhythms,which in turn influence metabolism and aging.Furthermore,we discuss the roles of functional metabolites as circadian cues,paving a new direction on potential intervention targets of circadian disruption,pathological aging,as well as metabolic diseases that are clinically important.
基金supported by the Science and Technology Program of Hebei Province, China (236Z2903G)the Innovative Research Group Project of Hebei Natural Science Foundation, China (C2024204246)+1 种基金the Hebei International Joint Research Center of Vegetable Functional Genomicsthe International Joint R&D Center of Hebei Province in Modern Agricultural Biotechnology for supporting this work。
文摘The plant circadian clock temporally drives gene expression throughout the day and coordinates various physiological processes with diurnal environmental changes. It is essential for conferring plant fitness and competitive advantages to survive and thrive under natural conditions through the circadian control of gene transcription. Chinese cabbage(Brassica rapa ssp. pekinensis) is an economically important vegetable crop worldwide, although there is little information concerning its circadian clock system. Here we found that gene expression patterns are affected bycircadian oscillators at both the transcriptional and post-transcriptional levels in Chinese cabbage. Time-course RNA-seq analyses were conducted on two short-period lines(SPcc-1 and SPcc-2) and two long-period lines(LPcc-1 and LPcc-2) under constant light. The results showed that 32.7–50.5% of the genes were regulated bythe circadian oscillator and the expression peaks of cycling genes appeared earlier in short-period lines than long-period lines. In addition, approximately 250 splicing events exhibited circadian regulation, with intron retention(IR) accounting for a large proportion. Rhythmically spliced genes included the clock genes LATE ELONGATEDHYPOCOTYL(BrLHY), REVEILLE 2(BrRVE2) and EARLY FLOWERING 3(BrELF3). We also found that thecircadian oscillator could notably influence the diurnal expression patterns of genes that are associated with glucose metabolism via photosynthesis, the Calvin cycle and the tricarboxylic acid(TCA) cycle at both the transcriptional andpost-transcriptional levels. The collective results of this study demonstrate that circadian-regulated physiological processes contribute to Chinese cabbage growth and development.
基金supported by grants from the National Natural Science Foundation of China(N0.82474525 and No.82074444)the Hunan Provincial Natural Outstanding Young People Science Foundation(2023JJ10032)the Hunan Province Health and High-Level Talent Medical Academic Leader Training Plan(20240304051).
文摘The circadian clock is an important internal time regulatory system for a range of physiological and behavioral rhythms within living organisms.Testosterone,as one of the most critical sex hormones,is essential for the development of the reproductive system,maintenance of reproductive function,and the overall health of males.The secretion of testosterone in mammals is characterized by distinct circadian rhythms and is closely associated with the regulation of circadian clock genes.Here we review the central and peripheral regulatory mechanisms underlying the influence of circadian clock genes upon testosterone synthesis.We also examined the specific effects of these genes on the occurrence,development,and treatment of common male diseases,including late-onset hypogonadism,erectile dysfunction,male infertility,and prostate cancer.
文摘Clock synchronization has important applications in multi-agent collaboration(such as drone light shows,intelligent transportation systems,and game AI),group decision-making,and emergency rescue operations.Synchronization method based on pulse-coupled oscillators(PCOs)provides an effective solution for clock synchronization in wireless networks.However,the existing clock synchronization algorithms in multi-agent ad hoc networks are difficult to meet the requirements of high precision and high stability of synchronization clock in group cooperation.Hence,this paper constructs a network model,named DAUNet(unsupervised neural network based on dual attention),to enhance clock synchronization accuracy in multi-agent wireless ad hoc networks.Specifically,we design an unsupervised distributed neural network framework as the backbone,building upon classical PCO-based synchronization methods.This framework resolves issues such as prolonged time synchronization message exchange between nodes,difficulties in centralized node coordination,and challenges in distributed training.Furthermore,we introduce a dual-attention mechanism as the core module of DAUNet.By integrating a Multi-Head Attention module and a Gated Attention module,the model significantly improves information extraction capabilities while reducing computational complexity,effectively mitigating synchronization inaccuracies and instability in multi-agent ad hoc networks.To evaluate the effectiveness of the proposed model,comparative experiments and ablation studies were conducted against classical methods and existing deep learning models.The research results show that,compared with the deep learning networks based on DASA and LSTM,DAUNet can reduce the mean normalized phase difference(NPD)by 1 to 2 orders of magnitude.Compared with the attention models based on additive attention and self-attention mechanisms,the performance of DAUNet has improved by more than ten times.This study demonstrates DAUNet’s potential in advancing multi-agent ad hoc networking technologies.
文摘A progressive decline in fertility is a well-documented aspect of female aging and is associated with a range of cellular and molecular alterations,including genomic instability and modifications in epigenetic regulation.Epigenetic clocks,which estimate biological age based on DNA methylation patterns,have been extensively utilized to evaluate general health status and the risk of various diseases.Despite their broad application,the utility of epigenetic clocks in assessing female reproductive health remains only partially characterized.This minireview consolidates recent advancements in the application of epigenetic clocks to evaluate the functional status of the female reproductive system.The objective is to investigate their potential for quantifying and predicting the biological age of reproductive tissues,thereby establishing a theoretical basis for clinical applications in reproductive medicine.To date,no comprehensive minireview has systematically examined multi-tissue epigenetic clock models in the context of female reproductive aging,positioning this minireview as a novel contribution to the field.
基金provided by CAS Project for Young Scientists in Basic Research(Grant No.YSBR-085)National Time Service Center(Grant No.E239SC1101)+1 种基金the funding of Wenzhou Major Science&Technology Innovation Key Project(Grant No.ZG2023021)supported by Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303200).
文摘Optical clocks with thermal atoms are characterized by compact size,simple structure,reduced weight,and low power consumption and have the potential for broad out-of-the-lab and commercial applications.Here,we demonstrate a 459 nm optical clock based on the 6S_(1/2)-7P_(1/2)transition in thermal^(133)Cs atoms.Two methods,modulation transfer spectroscopy(MTS)and frequency modulation spectroscopy(FMS),are employed to stabilize the frequency of a 459 nm commercial laser to the atomic transition.The MTS-MTS and MTS-FMS beat-note measurements show short-term frequency stabilities of 3.7×10^(-13)/√t and 6.4×10^(-13)/√t,respectively,at the averaging time t.The 459 nm passive optical clock further serves as the pump for an active 1470 nm optical clock based on the cavityless lasing.The resultant 1470 nm output power reaches over 10μW and the pump-beam-induced light shift is estimated to be 2π×11 Hz with a fractional uncertainty of 2.4×10^(-18).These results demonstrate the feasibility of hybridizing passive and active optical clocks,providing a promising route toward compact multi-wavelength optical frequency standards.
基金2023 Liaoning Institute of Science and Technology Doctoral Program Launch fund(No.2307B29).
文摘A clock bias data processing method based on interval correlation coefficient wavelet threshold denoising is suggested for minor mistakes in clock bias data in order to increase the efficacy of satellite clock bias prediction.Wavelet analysis was first used to break down the satellite clock frequency data into several levels,producing high and low frequency coefficients for each layer.The correlation coefficients of the high and low frequency coefficients in each of the three sub-intervals created by splitting these coefficients were then determined.The major noise region—the sub-interval with the lowest correlation coefficient—was chosen for thresholding treatment and noise threshold computation.The clock frequency data was then processed using wavelet reconstruction and reconverted to clock data.Lastly,three different kinds of satellite clock data—RTS,whu-o,and IGS-F—were used to confirm the produced data.Our method enhanced the stability of the Quadratic Polynomial(QP)model’s predictions for the C16 satellite by about 40%,according to the results.The accuracy and stability of the Auto Regression Integrated Moving Average(ARIMA)model improved up to 41.8%and 14.2%,respectively,whilst the Wavelet Neural Network(WNN)model improved by roughly 27.8%and 63.6%,respectively.Although our method has little effect on forecasting IGS-F series satellites,the experimental findings show that it can improve the accuracy and stability of QP,ARIMA,and WNN model forecasts for RTS and whu-o satellite clock bias.
基金supported by CAS Project for Young Scientists in Basic Research(Grant No.YSBR-085)the National Time Service Center(Grant No.E239SC1101)+1 种基金Innovation Program for Quantum Science and Technology(Grant No.2021ZD0303200)China Postdoctoral Science Foundation(Grant No.BX2021020).
文摘The phenomenon that a clock at a higher gravitational potential ticks faster than one at a lower potential,also known as gravitational redshift,is one of the classical tests of Einstein’s theory of general relativity.Owing to their ultra-high accuracy and stability,state-of-the-art optical lattice clocks have enabled resolving the gravitational redshift with a millimeter-scale height difference.Further reducing the vertical inter-clock separation down to the sub-millimeter level and especially shortening the required measurement time may be achieved by employing spin squeezing.Here,we theoretically investigate the spin-squeezing-enhanced differential frequency comparison between two optical clocks within a lattice-trapped cloud of^(171)Yb atoms.The numerical results illustrate that for a sample of 10^(4)atoms,the atomic-collision-limited resolution of the vertical separation between two clocks can reach 0.48 mm,corresponding to a fractional gravitational redshift at the 10^(-20)level.In addition,the required averaging time may be reduced to less than one hundredth of that of conventional clocks with independent atoms.Our work opens a door to the future spin-squeezing-enhanced test of general relativity.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB35010202)the National Natural Science Foundation of China(Grants No.62275268)。
文摘This study presents an achievement of laser cooling of alkaline-earth atoms in the Chinese Space Station’s strontium(Sr)atomic space optical clock.The system’s core components,physical unit,optical unit,and electrical unit,have a total volume of 306 L and a total mass of 163.8 kg.These compact and robust units can overcome mechanical vibrations and temperature fluctuations during space launch.The laser sources of the optical unit are composed of diode lasers,and the injection locking of slave lasers is automatically performed by a program.In the experiment,a blue magneto-optical trap of cold atoms was achieved,with the atom numbers estimated to be approximately(1.50±0.13)×10^(6) for 87Sr and(8.00±0.56)×10^(6) for 88Sr.This work establishes a foundation for atomic confinement and high-precision interrogation in space-based optical clocks and expands the frontiers of cold atom physics in microgravity.
基金supported by the Ministry of Science and Technology of the People’s Republic of China(Nos.2020YFA0803300 and 2021YFA0805600)the National Natural Science Foundation of China(Nos.92157113,82072630,82173114,82072903,82272872,82002811,82188102,and 82030074)+2 种基金the Zhejiang Natural Science Foundation Key Project(Nos.LD22H160002 and LD21H160003)the Zhejiang Natural Science Foundation Discovery Project(No.LQ22H160023)the Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang(No.2019R01001),China.
文摘The circadian clock is a highly conserved timekeeping system in organisms,which maintains physiological homeostasis by precisely regulating periodic fluctuations in gene expression.Substantial clinical and experimental evidence has established a close association between circadian rhythm disruption and the development of various malignancies.Research has revealed characteristic alterations in the circadian gene expression profiles in tumor tissues,primarily manifested as a dysfunction of core clock components(particularly circadian locomotor output cycles kaput(CLOCK)and brain and muscle ARNT-like 1(BMAL1))and the widespread dysregulation of their downstream target genes.Notably,CLOCK demonstrates non-canonical oncogenic functions,including epigenetic regulation via histone acetyltransferase activity and the circadian-independent modulation of cancer pathways.This review systematically elaborates on the oncogenic mechanisms mediated by CLOCK/BMAL1,encompassing multidimensional effects such as cell cycle control,DNA damage response,metabolic reprogramming,and tumor microenvironment(TME)remodeling.Regarding the therapeutic strategies,we focus on cutting-edge approaches such as chrononutritional interventions,chronopharmacological modulation,and treatment regimen optimization,along with a discussion of future perspectives.The research breakthroughs highlighted in this work not only deepen our understanding of the crucial role of circadian regulation in cancer biology but also provide novel insights for the development of chronotherapeutic oncology,particularly through targeting the non-canonical functions of circadian proteins to develop innovative anti-cancer strategies.
基金Supported by the National Basic Research Program of China under Grant No 2013CB338002the National Natural Science Foundation of China under Grant No 11504430
文摘When applying Grover＇s algorithm to an unordered database, the probabifity of obtaining correct results usually decreases as the quantity of target increases. A four-phase improvement of Grover＇s algorithm is proposed to fix the deficiency, and the unitary and the phase-matching condition are also proposed. With this improved scheme, when the proportion of target is over 1/3, the probability of obtaining correct results is greater than 97.82% with only one iteration using two phases. When the computational complexity is O（ √M/N）, the algorithm can succeed with a probability no less than 99.63%.
